It's on. After Liberal Democrat leader Nick Clegg challenged Nigel Farage to an "open debate about whether we should be in or out of the EU" the UKIP leader has responded by saying he "can hardly wait" to take part.

Speaking to Sky News, Mr Farage said: "It is going to happen.

"You know, I've been an MEP for 15 years and been told by other politicians and many parts of the media that basically UKIP are mad, that our future is, of course, in the European Union and we've always argued actually that we'd be better off outside and economically, democratically, in terms of our own self-confidence,

"Now we're having that debate and I see that as big, big progress."

He went to say he would like both David Cameron and Ed Miliband to take part.

Both the Conservatives and Labour parties have effectively ruled out taking part, so it will be a head-to-head debate.

This is something the Liberal Democrats have welcomed, arguing it is only their two parties that have a clear in or out position.

Facing the possible electoral wipe-out of their 12 MEPs at the European elections in May, the Liberal Democrats are pursuing a pro-active nothing-to-lose strategy.

Nick Clegg hopes the party will attract as many of the estimated 35% of voters who consistently say they support Britain's membership of the European Union.

For UKIP, the strategy is based on the theory that all publicity can only be good. A national platform they hope - with an increasingly Eurosceptic electorate - could see them top the poll.

And that leaves the question of where you will be able to see or hear this debate.

Negotiations will take place shortly to decide what format it will take. Both parties say they are open to having it on Sky News, but no decision has been made - so watch this space.